The present invention concerns a control system for an actuator for the actuation of submarine devices, such as valves for closing and opening submarine ducts.
Plants for transporting liquids and/or gases under the sea, for example the oil pipelines that run even for hundreds of meters under the sea, even at a depth of 3000 meters, comprise a plurality of intermediate stations in which valves for opening and closing the pipes or ducts the transport such liquids or gases are foreseen.
Such valves are actuated by submarine actuators that determine the opening and closing of such valves transmitting a rotation movement to the actuation shaft of the valve itself.
Such actuators are connected to the valves near to the submarine pipelines but must, however, be controlled from the surface or from remote control stations (also submarine).
Actuators are known that are actuated manually by a robot associated with a submarine that reaches the place where the valve and the actuator are situated and transmits the movement to the actuator itself through the robotised arm.
Hydraulic actuators are also known, which are actuated through a hydraulic station arranged at the surface having a hydraulic pipeline that connects such a station at the surface to the submarine actuator. The pipeline transports the hydraulic energy, for example compressed air, necessary for the actuation of the valve, on the bottom of the sea where the actuator is situated.
The Applicant has observed that hydraulic type actuators require the presence of an extremely large surface station of substantial environmental impact. Indeed, in such a station it is necessary to generate the necessary hydraulic pressure to actuate the submarine actuator and, moreover, the hydraulic cable suitable for transferring the hydraulic energy to the actuator must have substantial resistance to external pressure, since such actuators can be positioned in transportation plants even 3000 meters under the sea. All of this can determine insufficient reliability of the valve and of the plant as a whole, since the cable that transports the hydraulic energy under the sea could be damaged and therefore could jeopardise the good operation of the valve.
On the other hand, actuators that can just be actuated manually require the use of a submarine to carry out the operation of changing the status of the valve. Such an operation is both complex and expensive and does not allow the valve of the submarine transportation plant to be controlled in real time from the surface.
The Applicant has set itself the problem of making the actuation of a valve applied to a submarine pipeline from the surface or from whatever remote control station reliable.